Found this problem looking in my old textbook:

IfAttachment 26388,find the numerical value of the ratioAttachment 26389.

I started cross multiplying & I got stuck quite easily. How do I finish this?

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- Dec 28th 2012, 03:54 PMzachd77proportions - heavy algebra needed
Found this problem looking in my old textbook:

**If**Attachment 26388,**find the numerical value of the ratio**Attachment 26389.

I started cross multiplying & I got stuck quite easily. How do I finish this? - Dec 28th 2012, 04:05 PMabenderRe: proportions - heavy algebra needed
Use a common denominator.

- Dec 28th 2012, 04:24 PMzachd77Re: proportions - heavy algebra needed
I agree with your advice, but would I then solve for a/b?

- Dec 28th 2012, 04:59 PMabenderRe: proportions - heavy algebra needed

- Dec 28th 2012, 05:45 PMzachd77Re: proportions - heavy algebra needed
thanks I remember attempting this problem a few years ago, didn't turn out well.

- Dec 28th 2012, 10:26 PMibduttRe: proportions - heavy algebra needed
Alternatively:

(4a-9b)/4a= (a-2b)/b Just cross multiply and we get

4ab – 9b^2 = 4a^2 – 8 ab

Or 4a^2 – 12 ab + 9 b^2 = 0

( 2a )^2 – 2 ( 2a) ( 3b) + ( 3b)^2 = 0

( 2a – 3b)^2 = 0

That gives a = 1.5 b